Which is the most reactive carbanion and why???????

dear sowmya 
in carbanion , a carbon atom make 3 bonds and bears a formal negative charge in at least one of its resonance form , it is actually a reaction intermediate and is very reactive . 
a carbon which is more reactive is less stable , which is concluded by comparing among the other given options . 
TRICKS TO FIND OUT – ITS STABILITY INCREASE IN CASE ANY WITHDRAWING GROUP WILL BE THEIR . 
kindly attach the question for better explanation 
regards